The present invention relates to an inflator for inflating an airbag which is installed in a vehicle including an automobile and, more particularly, to an inflator which generates gases in multiple stages. The present invention further relates to an airbag device having the inflator.
An airbag device protects an occupant by an airbag which is inflated by gases generated by an inflator.
Japanese patent publication 9-136604 discloses an inflator having a casing which is divided into two small combustion chambers, each of which is filled with gas generating agents. By igniting the two combustion chambers at different timings, the airbag is adjusted in its inflation speed and the inflation continuing time period. When a collision is made in small magnitude, only one of the combustion chambers is ignited.
As clearly shown in the drawings of the publication 9-136604, the inflator has the first combustion chamber disposed at one end side and the second chamber disposed at the other end side of the casing, and gas spout holes are formed in the respective middle portions in the longitudinal direction of the combustion chambers. Therefore, when gas spouts only from the first chamber, gas is introduced only from the one end side of the casing into the airbag so that a one-end-side portion of the airbag is inflated quickly and largely as compared to the other-end-side portion of the airbag. In the same manner, when gas spouts only from the second chamber, gas is introduced only from the other end side of the casing into the airbag so that the other-end-side portion of the airbag is inflated quickly and largely as compared to the one-end-side portion of the airbag.
It is an object of the present invention to provide an inflator which inflates an airbag in bilateral symmetry as a whole and to provide an airbag device having the inflator.
An inflator of the present invention has a cylindrical casing, at least one partition defining a plurality of chambers in the casing which is arranged in the longitudinal direction of the casing, gas generating agents filled in the chambers, and gas spout holes formed in the casing. The holes are disposed close to the middle in the longitudinal direction of the casing.
An airbag device of the present invention has a container, an airbag folded and accommodated in the container, and the inflator of the present invention for inflating the airbag.
In the airbag device having the inflator as mentioned above, no matter whether gas spouts from either of the chambers, the gas spouts from substantially the middle or the vicinity of the middle in the longitudinal direction of the casing of the inflator whereby the airbag is inflated into a bilaterally symmetrical configuration as a whole.
It is preferable that the inside of the casing is divided into two chambers by the partition. Particularly, it is preferable that the partition is disposed to be offset from the middle in the longitudinal direction of the casing to one end side of the casing so that the casing has a first chamber on the one end side and a second chamber on the other end side, and that the holes formed in the first chamber are disposed close to the partition and the holes formed in the second chamber are disposed about the middle in the longitudinal direction of the casing.
In the airbag device, it is preferable that the container has a configuration elongated in the longitudinal direction of the inflator, the partition of the inflator is disposed to be offset from the middle in the longitudinal direction of the container to one end side of the container, the holes formed in the first chamber on the one end side are disposed as close to the middle in the longitudinal direction of the container as possible, and that the holes formed in the second chamber on the other end side are disposed about the middle in the longitudinal direction of the container.